IDS Forum

Re: Using complete CPU core instead thread

Posted By: Martin Furderer
Date: Thursday, 22 February 2018, at 6:37 a.m.

In Response To: Re: Using complete CPU core instead thread (Lester Knutsen)

I agree with Lester that it is better to turn off HyperThreading rather than turning off individual CPUs (i.e. those additional CPUs that the OS shows as a result from the HyperThreading being active).

If you have some other application(s) runnning on the system for which you want HyperThreading to be on ... then you may have no other choice than to individually turn off the "HyperThreading CPUs" of those cores that you want to give to the Informix Server. I'm not sure what exactly this then means in terms of process scheduling (from the perspective of the OS). I think you somehow will have to test. There are many factors that may influence performance, beginning with the Linux kernel version, and ending with the nature of the application workload.

If your system is I/O bound because there is a bottle neck with those two disks containing 3 TB of data, then optimizing CPU utilization probably has very little effect on overall performance. If the Informix threads doing the CPU intensive work are waiting for I/O of data, then they will just do that - wait for the data (and in the meantime not burn CPU cycles in a useless manner, fortunately).

Regards, Martin

--
Martin Fuerderer
Informix Development Germany

e-mail: martin.furderer@hcl.com

HCL Technologies Germany GmbH
Frankfurter Ring 17
80807 Munich, Germany
http://www.hcltech.com/de

--DISCLAIMER--
------------------------------------------------------------------------------------------------------------
This document is intended for transmission to the named recipient only. If you are not that person, you should note that legal rights reside in this document and you are not authorized to access, read, disclose, copy, use or otherwise deal with it and any such actions are prohibited and may be unlawful. The views expressed in this document are not necessarily those of HCL Technologies Ltd. Notice is hereby given that no representation, contract or other binding obligation shall be created by this e-mail, which must be interpreted accordingly. Any representations, contractual rights or obligations shall be separately communicated in writing and signed in the original by a duly authorized officer of the relevant company.
------------------------------------------------------------------------------------------------------------

________________________________
From: ids-bounces@iiug.org <ids-bounces@iiug.org> on behalf of Lester Knutsen <lester@advancedatatools.com>
Sent: Wednesday, February 21, 2018 20:26
To: ids@iiug.org
Subject: Re: Using complete CPU core instead thread [40726]

Michael,

It is better to Hyper-threading off in the BIOS then from the command line but
this is how we do it.

Here are some notes from our Informix Performance Tuning class on how to do
this.

To See CPU usage:
cat /proc/cpuinfo
Look for the CPUs that have the same "core id", you want to switch off the
second of each pair

And a script to disable it on our systems.
#############################################################################
## Module: @(#)informix.env 2.0 Date: 01/01/2015
## Author: Lester Knutsen Email: lester@advancedatatools.com
## Advanced DataTools Corporation
#############################################################################
## Disable CPU 4-7 to turn off Hyperthreading
echo 0 > /sys/devices/system/cpu/cpu4/online
echo 0 > /sys/devices/system/cpu/cpu5/online
echo 0 > /sys/devices/system/cpu/cpu6/online
echo 0 > /sys/devices/system/cpu/cpu7/online
#############################################################################

Make sure you are disabling the second of each pair... the cpu numbers may be
different on your system.

Make sure you test, depending on your system it may or may not be faster. One
our training servers, with 4 Physical Cores and 8 Virtual Cores, running 8
oninit CPUVP's on the 4 Physical Cores can be faster then running 8 oninit
CPUVP's on 8 Virtual Cores, it all depends on your workload.

Regards - Lester

On 2/20/18 5:28 PM, R MICHAEL wrote:
> Hi Martin,
>
> Thanks for your detailed response.
> Why I asked this question? Is because We have lots of CPUs available( real
> ones) and I can use only a small percentage because of the 3TB database is
> stored on only 2 disks and I can't take advantage of all those CPUs. So I
> wanted to use, somehow, the whole CPU core instead of a thread.
> I needed to know if I take offline every second CPU thread, the remaining
> online thread will have the computation power of the whole CPU core so that
I
> could use it as Informix VP.
>
> Thank you,
> Michael.
>
>
>
*******************************************************************************
> Forum Note: Use "Reply" to post a response in the discussion forum.
>

--
______________________________________________________________________
Lester Knutsen lester@advancedatatools.com
Advanced DataTools Corporation Voice: 703-256-0267 x102
Visit our Web page: https://apac01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.advancedatatools.com&data=02%7C01%7Cmartin.furderer%40hcl.com%7C65f34282e7ae4164dc2208d579611983%7C189de737c93a4f5a8b686f4ca9941912%7C0%7C0%7C636548380326823313&sdata=w9HIRN1ADeoV8rzM3UyjXvR6KOowB60EqSY%2FXiBql0k%3D&reserved=0
______________________________________________________________________

*******************************************************************************
Forum Note: Use "Reply" to post a response in the discussion forum.

::DISCLAIMER::
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
The contents of this e-mail and any attachment(s) are confidential and intended for the named recipient(s) only. E-mail transmission is not guaranteed to be secure or error-free as information could be intercepted, corrupted, lost, destroyed, arrive late or incomplete, or may contain viruses in transmission. The e mail and its contents (with or without referred errors) shall therefore not attach any liability on the originator or HCL or its affiliates. Views or opinions, if any, presented in this email are solely those of the author and may not necessarily reflect the views or opinions of HCL or its affiliates. Any form of reproduction, dissemination, copying, disclosure, modification, distribution and / or publication of this message without the prior written consent of authorized representative of HCL is strictly prohibited. If you have received this email in error please delete it and notify the sender immediately. Before opening any email and/or attachments, please check them for viruses and other defects.
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

Messages In This Thread

• Using complete CPU core instead thread
  R MICHAEL -- Sunday, 18 February 2018, at 12:45 p.m.
  • Re: Using complete CPU core instead thread
    BENJAMIN THOMPSON -- Monday, 19 February 2018, at 3:49 p.m.
    • Re: Using complete CPU core instead thread
      R MICHAEL -- Tuesday, 20 February 2018, at 8:58 a.m.
      • Re: Using complete CPU core instead thread
        Martin Furderer -- Tuesday, 20 February 2018, at 10:59 a.m.
        • Re: Using complete CPU core instead thread
          R MICHAEL -- Tuesday, 20 February 2018, at 5:28 p.m.
          • Re: Using complete CPU core instead thread
            Lester Knutsen -- Wednesday, 21 February 2018, at 2:26 p.m.
            • Re: Using complete CPU core instead thread
              Martin Furderer -- Thursday, 22 February 2018, at 6:37 a.m.
              • Re: Using complete CPU core instead thread
                R MICHAEL -- Thursday, 22 February 2018, at 1:04 p.m.
            • Re: Using complete CPU core instead thread
              R MICHAEL -- Thursday, 22 February 2018, at 12:47 p.m.

IDS Forum is maintained by Administrator with WebBBS 5.12.